Field of the Invention
This invention relates generally to train control systems, and more specifically to a train control system that is based on a generic new architecture that can be customized to the functional, operational, and safety requirements, as well as the operational environments of various railroad and transit properties. This generic architecture also provides a structured approach to achieve interoperability between different suppliers that employ different technologies or different design solutions to implement train control systems. The architecture can also be used to provide interoperability between two railroad operations that share common track.
Since the invention of the track circuit by William Robinson in 1872, train control systems have evolved from the early fixed block, wayside technologies, to various fixed block, cab-signaling technologies, and in recent years to communications based train control (CBTC), A.K.A. moving block technologies. In a CBTC system a train receives a movement authority from a wayside device, and generates a stopping profile that governs its movement from its current position to the limit of the movement authority. There are a number of possible variations of these basic technologies, and which operate by converting either a wayside signal aspect or a cab signaling speed code into a corresponding movement authority limit.
A train control system normally includes three main elements. The first element provides interlocking control and safety functions that enable trains to operate safely in the approach to, and over track switches (interlockings). Typically, the interlocking control element provides safety functions, including switch locking function when a train is operating in the approach to, or over a switch; route locking functions to protect against conflicting and opposing train moves at an interlocking; and traffic locking functions to protect against opposing moves between interlockings.
The second element provides a number of safety functions related to train movements. These functions include: train detection, safe train separation, and over-speed protection. The third element, known as Automatic Train Supervision (ATS), is normally non-vital, or non-safety critical, and provides service delivery functions, including centralized traffic control, automatic routing, automatic dispatching, schedule adherence and train regulation. The level of integration between these three elements of a train control system is a design choice. For example, a highly integrated CBTC system provides both train control and interlocking functions in a single element, and has a subsystem that provides the ATS functions.
One factor or characteristic that is common to these basic technologies is that the various physical elements of a train control system are installed in a railroad operating environment, and interact directly with each other. For example, a train detection, or location determination subsystem interacts with an interlocking controller for the purpose of implementing a switch locking function. However, the actual implementation of a specific train control function can vary greatly from railroad to railroad, as well as from supplier to supplier depending on the technology employed, and the specific design choice used. Another example is the interaction between wayside zone controller and a car borne controller in a CBTC system. Normally, a train sends its location to the zone controller, and in turn, the zone controller sends a movement authority limit to the train. This interchange of data between two physical components of the CBTC system, installed in a railroad operating environment, makes it challenging and to a certain extent difficult to achieve interoperability between different suppliers. In addition, train control implementation on a specific railway or transit property requires customization of the supplier's system, or technical platform, in order to meet the specific functional, operating and performance requirements of the railway or transit property.
Accordingly, there is a need for a new approach to streamline the customization of a supplier's train control system to the specific requirements of a rail property, as well as to facilitate interoperability between suppliers and railroads using shared tracks.
Description of Prior Art
In a fixed block wayside signal system, the tracks are divided into a plurality of blocks, wherein each block includes a train detection device such as a track circuit or axle counters to detect the presence of a train within the block. Vital logic modules employ train detection information to activate various aspects at a plurality of wayside signals in order to provide safe train separation between trains. An automatic train stop is normally located at each wayside signal location to enforce a stop aspect.
Cab-signaling technology is well known, and has evolved from fixed block, wayside signaling. Typically, a cab-signal system includes wayside elements that generate discrete speed commands based on a number of factors that include train detection data, civil speed limits, train characteristics, and track geometry data. The speed commands are injected into the running rails of the various cab-signaling blocks, and are received by trains operating on these blocks via pickup coils. A cab-signal system also includes car-borne devices that present the speed information to train operators, and which ensure that the actual speed of a train does not exceed the safe speed limit received from the wayside.
CBTC technology is also known in the art, and has been gaining popularity as the technology of choice for new transit properties. A CBTC system is based on continuous two-way communications between intelligent trains and Zone controllers on the wayside. An intelligent train determines its own location, and generates and enforces a safe speed profile. There are a number of structures known in the art for a train to determine its own location independent of track circuits. One such structure uses a plurality of passive transponders that are located on the track between the rails to provide reference locations to approaching trains. Using a speed measurement system, such as a tachometer, the vital onboard computer continuously calculates the location and speed of the train between transponders.
The operation of CBTC is based on the moving block principle, which requires trains in an area to continuously report their locations to a Zone Controller. In turn, the Zone Controller transmits to all trains in the area a data map that contains the topography of the tracks (i.e., grades, curves, super-elevation, etc.), the civil speed limits, and the locations of wayside signal equipment. The Zone controller, also, tracks all trains in its area, calculates and transmits to each train a movement authority limit. A movement authority is normally limited by a train ahead, a wayside signal displaying a stop indication, a failed track circuit, an end of track, or the like. Upon receiving a movement authority limit, the onboard computer generates a speed profile (speed vs. distance curve) that takes into account the limit of the movement authority, the civil speed limits, the topography of the track, and the braking characteristics of the train. The onboard computer, also, ensures that the actual speed of the train does not exceed the safe speed limit.
In addition to the above three basic technologies, there are a number of hybrid systems that combine certain structures of the basic technologies. For example, a Hybrid CBTC system employs traditional wayside fixed blocks with associated cab-signal control devices, as well as intelligent CBTC car borne equipment. The cab-signal control devices generate discrete speed commands that are injected into the running rails of the various cab-signaling blocks. In turn, an intelligent CBTC car borne device determines the location of the associated train, and generates a movement authority limit (MAL) based on the speed commands received from the wayside cab-signaling devices.
The current invention provides a generic virtual train control system that is based on concepts employed in the prior art, as well as new concepts disclosed in this invention. The elements of a physical or real train control system are indirectly interconnected to virtual train control application platforms through corresponding elements in the generic virtual system. This approach eliminates the need for direct interactions between the physical elements of a train control system and the train control application platform. The introduction of a generic virtual system simplifies the implementation of a train control system, and facilitates interoperability between suppliers. In the proposed architecture, the focus of interoperability is on the interfaces are between physical elements and corresponding virtual elements, rather than on the interfaces between the physical elements and the train control application platforms.